Burr plate



Nov; 18, 1930.

W. M. TOMASHEK BURR PLATE.

2 Sheets-Sheei 2 Filed Aug; 15, 1929 Patented Nov. 18, 1930 1 WILLIAM M. ronasnnigor inona,

EiSS

UNITED-STATES PATENT OFFICE MINNESOTA, ASSIGNOR To wINoNA ATTRITION MILL COMPANY, or WILTONAQMINN'ESOVTA, A CORPORATION or MINNESOTA was. PLATE Application filed August 15, 1929. Serial a... 386,030.

The invention relates to burr plates and has as an object the provision of a plate which will grind grainto a uniform fineness.

It is a. further object of the invention to provide a burr plate which. will 'grindgrain with less expenditure of power than plates heretofore known.

It is a further object of the invention w provide a burr'plate which willgrind' grain without heating the same. I

It is a further object of the invention to provide a plate made up of sections which may be assembled upon 'a support for use.

It is a further object of the invention to providea plate made up of sections so formed as to strengthen the portions necessary for greatest strength with the'least material,

Further objects of the invention will appear from the following description when read in connection with the accompanying.

drawings showing an illustrative embodiment of the invention and wherein F 1 is an elevation of an assembled plate;

Fig. 2 is a rear an enlarged scale; a v V a Fig. 3 is a front elevation of one section; Fig. 4 is an inside edge viewofone section and f 7 Figs. 5, 6, and '7 are sections taken upon the corresponding lines of Fig. 3.

As shown the assembled plate comprises an annular plate 10 made up of a. plurality of like sections 11 as illustrated in Figs. 2 to 7 inclusive. As'there shown each section comprises a plate which'is segment of the anelevation of one section on nulus and presents a front or working surface The sect ons are de-' signed to be assembled upon a disc or annular l2 and a rear surface 13.

support and to be secured theretoby bolts, the heads of which will be received in the taf pered openings 14:, which bolts will clamp the sections upon the support. I

c It is to be u'nd rstood that the said supports will be revolved in opposite directions or one support will berevolved while the other support may beheld stationary, two ofthe assembled annuli 10 being placed in opposed rela-' tion and separated to a distance corresponding to the fineness of the product deslred, 1n the manner well understood'in the art.

: projecting rearwardly c with cavities 18 cavities 18 ormateriahas to the cavities for the purpose of ren ovlng. For thepur-v Tocontact with the support, there is shown sembled in the balancing of theasseinbly ad-' 5 ditional material may be drilled out ofthe or adding weight as needed. pose'of retaining lead in the cavities, the cavities are preferably made of a dovetail cross sectionas indicated at 19in Fig. 5.

The front or Working surface of each of sections 12 is shown as formed with. a peripheral flange 20 standing above said work ing shrface and with a plurality of radial ribs 21 rising from the surface into of the edge of the peripheral flange 20 and the plane the 'outer portion of. said working surface,

' of the flange 20 and of the. ribs 21, are in planes normal to the axis of the annulus, whereas the inner margin of theworking surface from substant ally the circumferential line ,22 is sloped away from the plane normal to the axis of the annulus, as clearly indicated in Figs. 4: to 7 inclusive.

The surface ofthe ribs parallel with. the working a surface.

The ribs 21 are shown asterminating'short ofthe inner edge of the sections. ;Inter-. spersed with the ribs 21, there are showna.

plurality of ribs 23 which extend tothe in ner edge of the section and are oircumferem tially widened at their inner ends as indi-,

cated at 24for the purpose of feeding I113.

'terialto the working surface of thesections 21 is substantially lead,-may be added 2 and assembled annulus, the outer edge ofthe i ribs 23 and of the widened portions 24 be ingalso substantially parallel with the work 3 ing surface throughout. As an additlonal feeding means, there is shown a boss 25 placed between adjacent widened portions 2e and ribs 23 which is shown as rising to a less height than said widened portions which boss may or may not be exactly in alignment with one of the ribs 21 and is not necessarily centrally placed between the widened portions 2% of the ribs 23.

To control the progress of the feed to the outer periphery of the annulus, there are shown circumferential ribs 26 extending between the ribs 21 and 23, three of such ribs being shown, which ribs rise to a less height than the radial ribs 21 and 23 from the working surface.

By virtue of the presence of the ribs :26 feed will be checked in its outward morement and will be more thoroughly subjected to the shearing action of the relatively oppositely moving radial ribs upon the opposed annuli. The ribs 26 are shown as sloping upwardly from their bases to their apices for better passage of the material thereover. The working surface 12 is shown as sloping outwardly and upwardly to the surface of the peripheral flange 20 also for the better passage of material to discharge. it is understood that material will be fed through one of the opposed annuli and between the same to the working surfaces where it will be comminuted and will be dis charged radially of the plates at the periphery thereof between the opposed edges of the flanges 20.

Since the annulus 10 is made up of sections and since at least one of the annuli as placed in the mill will be revolved at a high rate of speed, the centrifugal strain upon the plates must be esisted by greater strength at the ends of the sections than at the centers, which ends are unsupported since they are not integ 'al with the end of the adjacent section. It i however drantageous to construct the e V e of the flai as thin as is consistent with the nee strength in order to reduce friction oi the discharging ground product to reduce heating thereof, and to conserve energy. To meet these requirements, the ends 27 of the peripheral flange 2O well as of the rearwardly projecting peripheral flange 15 are made thicker than the centers thereof, as clearly shown in Figs. 2 and 3.

To better preserve dynamic balance, the difference in thickness of the peripheral flanges 15 and 20 is compensated for by thickening the inner flange 16 at the center portion upon each section, as clearly indicated in Fig. 2.

For convenience in fitting the sections together at their ends, they are shown as formed with projecting portions 28, 29, 30, the surfaces of which may be ground to cause the assembled plates to accurately fit into a true annulus.

The ends of ribs2l are shown as sloping outwardly away from the working surface 12 as at 31 and the inner ends of the widened portions 24 of ribs 23 are shown rounded as at It is found that attention to each of the details of the plate as described results in the production of an attrition burr which will grind a considerable greater percentage of grain with the same power than any plate which applicant in a long experience has known and that the ground material leaving the plate is heated very little and to a markedly less extent than is the case with former known mills. The heat which has formerly been produced in the g inding of material is obviously a waste of enerov as well as being in many instances injurious-5 to the material. In addition to the named advantages the product ground by the plates of the invention is of a uniform fineness, being devoid of any considerable portion of powder.

Minor changes may be made in the physical embodiment of the invention within the scope of the appended claims without departing from the spirit of the invention.

I claim:

1. A burr plate comprising an annular member having a peripheral flange and a plurality of relatively closely spaced radial ribs flush with the edge of said flange, the surface of said member sloping outwardly to the outer edge of said flange, a plurality of circular ribs extending between said radial ribs, of less height than said radial ribs and describing circles unbroken except by intersection by radial ribs, certain of said radial ri 3; having circumferentially widened inne enus.

2. A burr plate comprising an annular plat e surrounded by a peripheral flange standing above its working so face, the said working surface sloping outwardly to the edge of said flange and said working surface sloping away from the general plane thereof at the iortion toward the axis of the annulus, a plurality of relatively closely spaced radial ribs rising above said working surface flush with said flange, some of said ribs terminating short of the inner edge of the annulus and others thereof having widened portions extending to said inner edge and a plurality of circumferential ribs projecting from said working surface to a less height than said radial ribs and describing circles unbroken except by intersection by radial ribs.

3. A burr plate comprising an annular member comprising a plurality of radially separate sections, each section formed with a peripheral flange relatively thin at the center of the circumferential extent of the section and thickened at the ends thereof, the working surface of the section sloping outwardly to the edge of the flange, a plurality of relatively closely spaced radial ribs flush with the edge of said flange and terminating short of the inner edge of the section interspersed by other radial ribs of like height extending to the said inner edge and widened at their inner ends and a plurality of circumferential ribs extending between said radial ribs and of less height than the radial ribs.

4. A burr plate comprising an annular plate comprising a plurality of radially sepa rate sections, each section formed with a pe- 1 ripheral flange relatively thin at the central portion of the circumferential extent of the section and widened at the ends thereof, the

workingsurface of the section, sloping outwardlyr adjacent theflange to the edge thereof, the central and outer portions of the Working surface of the said section radially there of lying in a plane normal to the axis of the annulus and the inner portion sloping away from said plane, a plurality of radial ribs rising above said working surface flush with said flange, certain of said ribs terminating short of the inner edge ofthe section and others thereof interspersed with said certain ribs extending'to said inner edge, saidextended ribs widened at their-inner endscircumferentially of the section, the free edges of said ribs substantially parallel with said working'surface and a plurality of circumferential ribs extending between and of less height than said radial ribs.

5. A burr plate comprising an annular member comprising a plurality of radially separate sections adapted to be assembled on a revoluble support, each section formed with a' peripheral flange projectingfrom the working and from the rear surface of the section, said flange being relatively thin at the center circumferentially of the section and thickened at the ends thereof, also 40 formed with a flange at its inner edge extending above its rear surface, said lastnamed flange thickened at its central portion and with bolt receiving openings and a lug adjacent each opening rising to the plane of the rear edge of said flanges, a plurality of radial ribs rising from the working surface of each section flush with the edge of said peripheral flange, certain of said ribs terminating short of the inner edge of the section and others of 5 said ribs interspersed with said certain ribs extending to said inner edge and circumferentially widened adjacent said edge.

WILLIAM M. TOMASHEK. 

